The present invention relates to a connecting tool substantially for use in association with wire connections for electricity or signalling which have to be brought into contact in a connecting clamp.
The connecting tool is provided with knife segments which, when the connecting tool is in use, remove the insulation on a part of the wire connection or displace parts of the insulation before the wire connection by connecting the connecting tool in a connecting clamp. The connecting tool can therefore be used both in association with uninsulated wire connections which have to be brought into connection in a connecting clamp, as well as insulated wire connections whose insulation has to be removed in an area before being brought into contact in a connecting clamp or the like.
Wire connections of various kinds are used for transferring electricity, data and telephone signals and the wire connections are terminated in contact points of different types depending on the area of application and the type of wire. The work of terminating wire connections in contact points is normally performed by a tradesman who is familiar with the existing requirements at any time concerning the wire""s connection with a contact point. Thus it will be important for a tradesman to have available at all times the tools necessary for making a connection between a wire and a contact point which satisfies the existing requirements regarding connection, while being able to perform this task within a reasonable time and in an efficient manner. This is particularly important where several operations are necessary in order to make a connection between a wire and a contact point. The most common operations in this connection are to remove the insulation from the end of the wire after adapting the length and position of the wire, and subsequently to fit the stripped part of the wire in the contact point and secure the wire to the contact point.
There are at present a plurality of different types of contact points for use in transferring electricity, data signals, telephone signals and the like. Two main groups of such contact points, however, have different systems for connecting a wire connection.
A common type of connection is a screw connection where the stripped wire connection is mounted beside or partly round a screw which is then tightened, thus forming a secure connection between the screw, the earth connection in which the screw is mounted and the stripped part of the wire connection.
This type of wire connection requires a succession of operations which are relatively time-consuming and the quality of the result of the connection is entirely dependent on the skills of the tradesman. There is therefore every possibility that a screw connection may result in an unsatisfactory wire connection if, for example, the screw is not tightened sufficiently, or the stripped part of the wire is incorrectly mounted in connection with the screw. Moreover, screw connections are subject to change over time, particularly if the screw connection is performed in an operative environment, which, e.g., entails frequent or large temperature fluctuations, vibrations and dynamic loading, or if it is exposed to other influences on the material in the screw connection. The contact between the wire and the screw connection, e.g. when transferring electricity, will develop heat, and if the surrounding environment has a temperature which deviates significantly from the temperature in the screw connection during the transfer of electricity, the screw connection may lose its tension round the stripped wire. This may cause the intermediate resistance between wire and screw connection to increase, which in turn may lead to dangerous situations, both in connection with heat development in the contact and in connection with unsatisfactory contact. If the contact supplies important appliances with electricity or signals, poor contact and a possible break could lead to serious problems. Similarly, overheating and potential fire in the contact could also result in dangerous and serious situations. In order to overcome the said problem, the clamping force between the screw connection and the stripped wire must be kept constant and high enough to ensure a good connection with low intermediate resistance.
Alternatively, a clamp device may be employed as contact point where the stripped wire is pushed into an opening in an electrically conductive, preferably metallic material, which opening is adapted to the cross sectional dimension of the stripped wire, with the result that the clamp conveys an adequate clamping force to the wire. The use of such a clamp device is time-saving since fewer operations require to be performed in connection with the fitting of the stripped wire in the clamp. However, special tools have to be employed to push the wire into position in the clamp, particularly since the clamp has to be designed in such a manner that it conveys sufficient clamping force round the wire. A clamp device of this kind is not subject to problems in connection with repeated heating and cooling to as great an extent as the screw device, as long as the material in the clamp device is stable. Thus the clamp device does not require to be inspected to the same extent as a screw contact after the wire has been fitted in the clamp device. In connection with a clamp contact, however, a special tool has to be employed to bring the wire connection into contact therein and the present invention relates to a connecting tool for mounting a wire connection in a clamp contact. In a preferred embodiment the connecting tool can further remove the insulation from the wire in the same operation as that in which the wire is pushed into contact with the clamp device.
Of previously known solutions relating to similar connecting tools reference should especially be made to publication DE 2739247-B1 which concerns a tool for inserting an insulated electrical conductor in the clamp opening of a clamp element. As in the case of the present invention the solution in the said publication may also remove the insulation from a wire and subsequently push it into contact in a clamp device. In the said publication the insulated wire abuts against a displacement element in the tool, which element moves the insulated wire past two knife edges which cut away the insulation before the movable element further moves the stripped wire into connection in the contact clamp. In order to be able to employ the tool in the said publication the wire connection from which the insulation has to be removed has to be placed over the knife edges, in the area between the upper edge of the knife edges and the lower edge of the movable element. Furthermore, the tool will only have support against the contact clamp as long as the outer edges of the tool housing are located around the clamp and when the movable element passes out under the housing""s lower edge the tool has little support and insufficient control round the clamp device. Moreover, it will not be possible to provide the lower end of the movable element with a corbelled shape which provides support round the clamp element as it will come into conflict with the clamp element when the movable element passes the lower edge of the tool""s housing. Alternatively, the movable element may be provided with a corbelled shape which is adapted to the size of the clamp element, with the result that it will abut against and give support at the clamp element, but this will entail a larger dimension for the tool housing which in turn means that the tool housing cannot provide support round the clamp element in the initial part of the process where the movable element is pushed down against the clamp element. This in turn means poor support and control in the part of the application process where the insulation is removed from the wire connection inside the tool.
A further known solution within the same field is described in U.S. Pat. No. 5,099,570 which focuses to a greater extent on setting up the tool relative to the contact. In this case, however, the tool has a different function to some extent and the insulation is removed from the wire in a different way. The solution therefore addresses only parts of the problem which is solved in the present invention.
In comparison with previously known solutions as described above, the present invention provides a tool which both removes the insulation from a part of the wire connection and clamps it in position in a clamp device.
The device according to the present invention is so designed as to provide good control in connection with the clamp device in order to ensure that the wire connection is correctly pushed into position in the clamp device. Furthermore, the tool is designed in such a manner that the wire connection is held steady relative to the knife edges which cut the insulation and helps to secure the displacement of the insulation, thus preventing remaining insulation residue from being pressed down into the clamp device together with the stripped wire connection. Furthermore in an alternative embodiment the connecting tool may be designed in such a manner that the tool has two opposite ends which are adapted to different wire cross sections where the tool can easily be converted so that the desired end can be used. The connecting tool according to the present invention is further described in the introduction to the following independent claim with characterising features as indicated in the characterising part of the independent claim. Furthermore, different embodiments of the connecting tool are indicated in the following dependent claims.